Tuesday, May 8, 2012

Monday, May 7, 2012

OK one more
I think I've figured out the value of twitter.  If you need to get a message to a bunch of people you can reach a whole audience with a single hashtag and don't have to create an address list.  Much easier.  I still thinks it's annoying, though.
On a more serious topic - I'm grading a lab.  There's an old saying about labs:  "If it smells bad it's Cemistry, if it's green or fuzzy, it's biology, and if it doesn't work it's Physics."

The lab had the students varying the length of a tube with a tuning fork vibrating at it's mouth and locating the lengths at which the tube resonated.  Then they figure out the wavelength and calculate the speed of sound.  NOBODY, not even I, found the fundamental.  We could hear the variation on volume fine, but couldn't find the shortest resonant length.  I've been trying to grade this thing for 2 days.   I decided to kind of pretend that they did find the fundamental, but what really bothers me are two things.  First, only a couple of the students acknowledged that their measurements were WAY off of theory.  It seems the only thing they learned is the old adage quoted above.  They don't worry if it doesn't work - as long as they know what format to write their report in (kind of like what I'm doing now).  The other thing is, why did I not catch it while it was happening?  I didn't design the lab, but why not run it the night before to make sure it worked?  (In self-defense against self-attack, I've done that with most of the labs)  And why not check their results on the fly (again, as I usually do) to make sure things were working out?  I guess that had to do with their working outside, widely separated, with no tables to set their notes on and for me to look over their shoulders at.  But I could have done it better by controlling the situation to the point where I could get a verbal response that would tell me where they were at.
At the risk of being disingenuous, I'm going to crank out a post or two for my blog.  I know I'll be considered insincere for going past the last minute, but there it is.

As it happens, I've opened up tweetdeck, as much as I don't like to, and found a stream of edchats going by, so I guess that'll be my subject for now.  I went to two edchats, only commented on one.  If you read the first post you know that my comment had to do with spam and, again, I find I can't much focus on the topic of the conversation as on what's between the lines.  I keep thinking about the deceptive scale of the internet.  All the marketing principles about how many times you have to hear something before you believe it, or before you click on 'BUY NOW' hold sway here.  Once upon a time there was a fad of placing a classified ad in a newspaper saying, essentially  "Please send me $5"  Enough people would do it that you could at least cover the cost of the ad.  With the internet, you can write a message like that, set it up to post and repost automatically, even with variations,  and reach hundreds of millions of eyes for just a few hours work.  So I have a deep suspicion of anything flowing through that pipe.

Meanwhile, tweetdeck is popping away and I've become acclimated, and arranged my screen so that it doesn't cover up what I'm doing, so now it's just a minor annoyance - but it still doesn't bring me any value.

Thursday, May 3, 2012

RC Time Constant
I had an idea.  Usually nobody does a lab with capacitors, even though students are supposed to know about them, because without automated equipment you can't measure current and voltage as a function of time.
So you could get a resistor and capacitor set with a time constant of about a second, have student set the voltmeter and ammeter next to each other and take a video while they close the switch.  Then using one of the video editing programmings you can step through the video frame by frame, that is every 0.02 seconds, and read current and voltage off the screen.  They could see the voltage across the cap increase as the current decreases and they would get too see an exponential function - which they don't get anywhere else.

Tuesday, May 1, 2012

When we do a DE in Science Methods, we generally end the demonstration by saying something like "What's going on here?" It's meant to make the students think deeply and  look for the thing we're not telling them.  So here goes.......

The other day I saw a classroom that contained 2 teachers, 40 laptops , 80 clickers and about 14 students.  A few years ago I volunteered in a classroom that had a smart board, 5 computers and 3 students.  What's going on here?

I stopped at 7-11 last night and the clerk was talking about this cool drinking game based on the TV show Big Bang Theory.  It seems that you watch the show and whenever a character does or says the trigger, you drink. Details can be found at http://weknowawesome.com/2012/03/17/the-big-bang-theory-drinking-game/ and other locations.   I said to him, “Well, you could do that with any show.”  He thought for a moment then replied, “Yeah, but Big Bang Theory is so cool!”
On the way out I realized that this fellow had been the recipient of a viral marketing campaign.   The main demographic of the show, men in their early twenties are in their prime binge-drinking years. If they can be convinced to take a shot every time a character says the word “sex” or some such thing well, you can sell an awful lot of booze that way.
The question that comes to my mind is:  “Does what we do every day as teachers help to inoculate the kids against that type of manipulation?  Or does it make them more susceptible?”  Alternatively:  “Does our educational system make students more observant, more aware, or not?”  At this point I’m concerned that the answer may be “not”.